JP2009031037A - Tolerance evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tolerance evaluation device for measuring a malfunction voltage of a semiconductor element simple body to an electrostatic noise. <P>SOLUTION: This device includes a DC power source generation part 4 for supplying an operation voltage of a semiconductor element 7, an electrostatic gun 1 for radiating the electrostatic noise in a prescribed direction, a bias tee 3 for superimposing the electrostatic noise on the operation voltage and applying it to the semiconductor element 7, a voltmeter 6 for measuring a logic level voltage value outputted corresponding to the voltage applied to the semiconductor element 7, and an oscilloscope 5 for measuring a voltage of the electrostatic noise applied to the semiconductor element 7 at the point of time when a logic of the logic level voltage value is inversed. The device also includes a branch circuit 2 inserted between the electrostatic gun 1 and the bias tee 3, for branching a part of the electrostatic noise radiated from the electrostatic gun 1 and supplying it to the bias tee 3; and a shielding part 8 for shielding the electrostatic gun 1, and preventing a noise not entering the branch circuit 2 in the electrostatic noises radiated from the electrostatic gun 1 from leaking to the outside. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tolerance evaluation apparatus for evaluating the tolerance of a semiconductor element to electrostatic noise.

  In an IC or LSI which is a semiconductor element included in a semiconductor device, a threshold voltage is determined with respect to a reference power supply voltage. Accordingly, when the induced voltage due to external noise from the outside exceeds the threshold voltage, a malfunction occurs.

  However, the threshold voltage is determined as a DC voltage, and cannot be applied to impulsive noise such as electrostatic noise. Further, in some conventional noise tolerance evaluation methods, the voltage level at the time of malfunction is determined in advance. However, when the voltage level is given in catalog specifications, there are very few (for example, see Patent Document 1). .

  On the other hand, if the voltage level when the semiconductor element malfunctions is known, as shown in Patent Document 1, the external noise part and the semiconductor device part (including the semiconductor element and wiring for operating the semiconductor element) are equivalent. It is possible to evaluate the malfunction of the semiconductor device by making a circuit, calculating the induced voltage applied to the semiconductor element by circuit analysis, and comparing the allowable voltage with the induced voltage.

  As another conventional noise tolerance evaluation method, there is a method for measuring a semiconductor element with respect to noise of a sine wave or an AM modulated wave (see, for example, Non-Patent Document 1). In this Non-Patent Document 1, in order to apply noise while operating a semiconductor element, an inductor is inserted between the DC power supply and the semiconductor element, and between the sine wave or AM modulated wave noise generator and the semiconductor element. A circuit for inserting a capacitor is disclosed. However, impulsive noise such as electrostatic noise is not described.

JP 2003-216682 A Monthly EMC (Mimatsu Corporation, December 2006, No. 224)

  In order to calculate the voltage level (hereinafter referred to as malfunction voltage) when a semiconductor device malfunctions due to electrostatic noise by numerical simulation based on Maxwell's equations such as electromagnetic field analysis and circuit analysis at the design stage, A malfunction voltage of a single semiconductor element included in the apparatus is required.

  That is, in the numerical simulation, only the voltage induced in the semiconductor element included in the semiconductor device when electrostatic noise is applied can be calculated. Therefore, if the malfunction voltage of the semiconductor element alone is not known, the presence or absence of malfunction cannot be determined. However, the conventional technology cannot measure the malfunction voltage of a single semiconductor element against impulsive noise such as electrostatic noise.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a tolerance evaluation apparatus that actually measures a malfunction voltage of a semiconductor element alone against electrostatic noise.

  A tolerance evaluation apparatus according to the present invention is supplied from a DC power source generating unit that supplies an operating voltage for operating a semiconductor element to be evaluated, an electrostatic gun that radiates electrostatic noise in a predetermined direction, and supplied from the DC power source generating unit. Depending on the bias voltage applied to the power supply pin of the semiconductor element by superimposing the electrostatic noise radiated from the electrostatic gun on the operating voltage to be applied, and the voltage applied to the semiconductor element connected to the output pin of the semiconductor element A voltmeter that measures the output logic level voltage value, and an oscilloscope that measures the voltage of electrostatic noise applied to the semiconductor element at the time when the logic level voltage value measured by the voltmeter is inverted, A resistance evaluation device that quantitatively evaluates the resistance of semiconductor elements to be measured against electrostatic noise, and is inserted between the electrostatic gun and the bias tee. A branch circuit that branches a part of the electrostatic noise radiated from the electrostatic gun and supplies it to the bias tee, and covers the electrostatic gun and does not enter the branch circuit among the electrostatic noise radiated from the electrostatic gun. And a shielding portion for preventing leakage of objects to the outside.

  According to the present invention, in order not to adversely affect the voltage measurement of electrostatic noise applied to the semiconductor element, electromagnetic radiation from other than the tip of the electrostatic gun is shielded, and an appropriate size is achieved by the action of the branch circuit. By applying the electrostatic noise to the semiconductor element to be measured, it is possible to obtain a tolerance evaluation apparatus that actually measures the malfunction voltage of the semiconductor element alone against the electrostatic noise.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of an apparatus for evaluating resistance to electrostatic noise of a semiconductor element according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing an equivalent circuit of the branch circuit 2 according to Embodiment 1 of the present invention. The electrostatic noise generated by the electrostatic gun 1 and electromagnetically radiated in a predetermined direction is bifurcated by the branch circuit 2, one of which is conducted to the semiconductor element 7 side via the resistor R1, and the other is electrostatic gun via the resistor R2. Conducted to the negative side of 1.

  The minus side of the branch circuit 2 is connected to the ground of the anechoic chamber 8 corresponding to the shielding part. Note that the branch circuit 2 is incorporated in the anechoic chamber 8 in advance. If the electrostatic noise applied to the semiconductor element 7 is too large and the malfunction voltage of the semiconductor element 7 cannot be measured simply by adjusting the output voltage of the electrostatic gun 1, the resistors R1 and R2 of the branch circuit 2 The static noise applied to the semiconductor element 7 can be reduced by changing the constant.

  The electrostatic noise that has passed through the resistor R 1 of the branch circuit 2 is applied to the power supply pin of the semiconductor element 7 via the bias tee 3. The bias tee 3 is composed of an LC circuit, and superimposes the electrostatic noise from the branch circuit 2 on the operating voltage of the semiconductor element 7 generated by the DC power supply 4 corresponding to the DC power supply generation unit, so that the power pin of the semiconductor element 7 To be applied. The ground pin of the semiconductor element 7 is connected to the negative side of the DC power supply 4, the negative side of the electrostatic gun 1, and the ground of the anechoic chamber 8, and electrostatic noise is returned to the negative side of the electrostatic gun 1.

  The semiconductor element 7 is an IC having a built-in flip-flop. A state in which the internal memory is fixed to high is normal, and the voltage at that time is measured by the voltmeter 6. More specifically, the voltmeter 6 measures the voltage value of the logic level output from the internal memory by measuring the voltage of the memory information output pin of the semiconductor element 7 as shown in FIG.

  When the output voltage of the electrostatic gun 1 is gradually increased and the internal memory of the semiconductor element 7 is changed from high to low by the voltmeter 6, it is determined as a malfunction. Therefore, the voltage level of the electrostatic noise between the power supply pin and the ground pin of the semiconductor element 7 at this time is measured with the oscilloscope 5, and the measured voltage is set as a malfunction voltage. In measuring the inversion of the voltage value of the logic level, it is also possible to measure the time point when switching to high with low being normal.

  According to such a configuration, electromagnetic waves radiated from other than the tip of the electrostatic gun 1 do not deteriorate the measurement accuracy of the measurement probe of the oscilloscope 5. This is because electromagnetic waves radiated from other than the tip of the electrostatic gun 1 are shielded by the anechoic chamber 8.

If the electrostatic noise applied to the semiconductor element 7 is too large to measure the malfunction voltage of the semiconductor element 7 simply by adjusting the output voltage of the electrostatic gun 1, the resistance R1, By changing the constant of R2, static noise applied to the semiconductor element 7 can be reduced. More specifically, the resistor R1 is increased, by reducing the resistance R2, it can be made larger than the I ₂ to I _1.

  FIG. 3 is an example of a measurement result when SN74LVC74ADB manufactured by TI is used as the semiconductor element 7 in the tolerance evaluation apparatus having the configuration of FIG. 1 in the first embodiment of the present invention. The voltage of the DC power supply 4 is 2.7V. When the output of the electrostatic gun 1 is increased and the voltage level of electrostatic noise between the power supply pin and the ground pin of the semiconductor element 7 measured by the oscilloscope 5 becomes 92 V, it has been found that the semiconductor element 7 malfunctions.

  Furthermore, the malfunction voltage of the semiconductor element 7 with respect to electrostatic noise and induction between the ground pin and the power supply pin of the semiconductor element 7 obtained by analyzing the semiconductor device by numerical simulation based on Maxwell's equations such as electromagnetic field analysis and circuit analysis. It is possible to calculate the malfunction voltage of the semiconductor device with respect to electrostatic noise by comparing with the voltage to be applied.

  As described above, according to the first embodiment, the electromagnetic radiation from other than the tip of the electrostatic gun is shielded in the anechoic chamber and does not adversely affect the voltage measurement of the electrostatic noise applied to the semiconductor element. The tolerance evaluation apparatus which has can be implement | achieved. Furthermore, by providing a branch circuit for finely adjusting the output of the electrostatic gun, the malfunction voltage of the semiconductor element against electrostatic noise can be measured with higher accuracy.

  Furthermore, the measurement result of such malfunction voltage is compared with the voltage induced in the semiconductor element calculated by numerical simulation based on Maxwell's equations such as electromagnetic field analysis and circuit analysis considering the noise propagation characteristics of the semiconductor device. By doing so, it becomes possible to evaluate the tolerance of the semiconductor device against electrostatic noise at the design stage.

Embodiment 2. FIG.
In the second embodiment, a case will be described in which a shield box 9 is used as a shielding portion instead of the anechoic chamber 8 as described in FIG. 2 of the first embodiment. FIG. 4 is a diagram showing an equivalent circuit of the branch circuit 2 according to Embodiment 2 of the present invention. The electrostatic noise generated by the electrostatic gun 1 is bifurcated by the branch circuit 2 as in the first embodiment, and one is conducted to the semiconductor element 7 side via the resistor R1, and the other is static via the resistor R2. Conducted to the negative side of the electric gun 1.

  However, in the second embodiment, the branch circuit 2 is installed outside the shield box 9. Further, the shield box 9 has an opening so that the tip of the electrostatic gun 1 can be connected to the branch circuit 2, and also has an opening for taking out the cable on the negative side of the electrostatic gun 1. .

  Further, in the second embodiment, a ground plate 10 is further provided, and the negative side of the electrostatic gun 1, the negative side of the DC power supply 4, the ground pin of the semiconductor element 7, and the shield box 9 are the ground plate. 10 is connected.

  According to such a configuration, electromagnetic waves radiated from other than the tip of the electrostatic gun 1 do not deteriorate the measurement accuracy of the measurement probe of the oscilloscope 5. This is because electromagnetic waves radiated from other than the tip of the electrostatic gun 1 are shielded by the shield box 9.

If the electrostatic noise applied to the semiconductor element 7 is too large to measure the malfunction voltage of the semiconductor element 7 simply by adjusting the output voltage of the electrostatic gun 1, the resistance R1 of the branch circuit 2 and By changing the constant of R2, static noise applied to the semiconductor element 7 can be reduced. More specifically, the resistor R1 is increased, by reducing the resistance R2, it can be made larger than the I ₂ to I _1.

  Furthermore, by providing a configuration using the shield box 9 and the ground plate 10 instead of the anechoic chamber 8, even if there is no large-scale facility such as the anechoic chamber 8, an electrostatic noise resistance evaluation apparatus can be provided at low cost. It becomes possible to build.

  As described above, according to the second embodiment, a configuration in which electromagnetic radiation from other than the tip of the electrostatic gun is shielded by the shield box and does not adversely affect the voltage measurement of electrostatic noise applied to the semiconductor element. The tolerance evaluation apparatus which has can be implement | achieved. Furthermore, by providing a branch circuit for finely adjusting the output of the electrostatic gun, the malfunction voltage of the semiconductor element against electrostatic noise can be measured with higher accuracy.

  Furthermore, the measurement result of such malfunction voltage is compared with the voltage induced in the semiconductor element calculated by numerical simulation based on Maxwell's equations such as electromagnetic field analysis and circuit analysis considering the noise propagation characteristics of the semiconductor device. By doing so, it becomes possible to evaluate the tolerance of the semiconductor device against electrostatic noise at the design stage.

  Furthermore, since the tolerance evaluation device can be realized by a configuration using a shield box and a ground plate instead of the anechoic chamber, it is possible to obtain a tolerance evaluation device with further cost reduction.

It is a block diagram of the tolerance evaluation apparatus with respect to the electrostatic noise of the semiconductor element in Embodiment 1 of this invention. It is a figure which shows the equivalent circuit of the branch circuit 2 in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is an example of the measurement result at the time of using SN74LVC74ADB by TI as the semiconductor element 7 in the tolerance evaluation apparatus of the structure of FIG. It is a figure which shows the equivalent circuit of the branch circuit 2 in Embodiment 2 of this invention.

Explanation of symbols

  1 electrostatic gun, 2 branch circuit, 3 bias tee, 4 DC power supply (DC power generation part), 5 oscilloscope, 6 voltmeter, 7 semiconductor element, 8 anechoic chamber (shielding part), 9 shield box (shielding part), 10 Ground board.

Claims (3)

A direct-current power generator that supplies an operating voltage for operating the semiconductor element to be evaluated;
An electrostatic gun that emits electrostatic noise in a predetermined direction;
A bias tee that is applied to the power supply pin of the semiconductor element by superimposing the electrostatic noise radiated from the electrostatic gun on the operating voltage supplied from the DC power supply unit,
A voltmeter connected to an output pin of the semiconductor element and measuring a logic level voltage value output in accordance with a voltage applied to the semiconductor element;
An oscilloscope that performs voltage measurement of electrostatic noise applied to the semiconductor element at the time when the logic of the logic level voltage value measured by the voltmeter is inverted, and is resistant to electrostatic noise of the semiconductor element to be measured A resistance evaluation device for quantitatively evaluating
A branch circuit that is inserted between the electrostatic gun and the bias tee and branches a part of electrostatic noise radiated from the electrostatic gun to supply the bias tee;
A resistance evaluation apparatus, further comprising: a shielding portion that covers the electrostatic gun and prevents leakage of electrostatic noise radiated from the electrostatic gun that is not incident on the branch circuit to the outside. .   The shielding portion covers the electrostatic gun and the branch circuit, and is configured by an anechoic chamber that prevents the electrostatic noise radiated from the electrostatic gun from entering the branch circuit from leaking to the outside. The tolerance evaluation apparatus according to claim 1.   The shield has an opening for allowing electrostatic noise radiated from the electrostatic gun to enter the branch circuit, covers the electrostatic gun so that the branch circuit is provided outside, and covers the electrostatic gun. The tolerance evaluation apparatus according to claim 1, wherein the static electricity noise radiated from the gun is configured by a shield box that prevents leakage of the noise not incident on the branch circuit to the outside.

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